The singer and Kourtney Kardashian were spotted spending some quality time together at The Nice Guy in West Hollywood, where Bieber performed two songs.
"He and Kourtney were nearly inseparable – smoking on the patio together and were super touchy feely," a source tells PEOPLE.
"They went to Blind Dragon afterwards," the source says. "Kourtney left around 12:45 a.m. and Justin left around 1:30 a.m."
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On Sunday, Bieber, 21, sparked a flurry of speculation that he and Kardashian, 36, were more than friends when he posted a photo on Instagram that seemingly referenced Kardashian ex Scott Disick
Bieber posted a photo with a mystery women, captioning it "Lord knows," which fans speculated was a reference Disick's nickname The Lord. However, paparazzi photos later revealed that the mystery woman in the Instagram post was not Kardashian.
Bieber has palled around with the Kardashian family in the past. In May, Bieber posted a photo of himself horsing around in a pool with Disick and Kardashian's son Mason.
"Mason is as cool as a fan," he captioned the photo.